Sometimes it doesn't just rain; it pours. For people living in Cumbria, that was exactly what happened in November 2009, when over 400mm of rain fell over the fell tops in three days, and in Borrowdale, a record-breaking 314.4mm of rain fell in one day. Many homes and businesses across the region were flooded, and in the town of Workington a policeman died when a bridge collapsed.

In this case Cumbria had the misfortune to be in the path of an "atmospheric river". Formed in the warm portion of mid-latitude storms, these narrow (around 200km wide) ribbons of moist air stretch for thousands of kilometres, and can carry a greater flux of water than Earth's largest river – the Amazon River. Every year around ten atmospheric rivers stall over the British Isles, bringing intense rainfall to a small region. The most vulnerable spots in the UK are the hilly areas in the north and west, especially those with small river catchments. If an atmospheric river hits one of these regions head-on, as it did in Cumbria in 2009, the resulting intense rainfall can be devastating.

Now new research, published in the journal Environmental Research Letters, suggests that the most intense atmospheric rivers are likely to become more frequent and more water laden by the end of the century, bringing misery to the UK.

"If the atmosphere warms, its moisture holding capacity increases, which will make atmospheric rivers more severe," says Richard Allan, from Reading University, one of the authors on the study.